[Not Applicable]
1. Field of the Invention
The present invention relates to molds for golf balls. More specifically, the present invention relates to a mold to impart an alternating parting line on a golf ball.
2. Description of the Related Art
Golf balls generally have either a one-piece construction or they may comprise several layers including a core, one or more intermediate layers and an outer cover that surrounds any intermediate layer and the core.
Golf balls are typically manufactured by various molding processes, whether one-component or multi-component balls. Generally, the core of the golf ball is formed by casting, compression molding, injection molding or the like. If an intermediate boundary layer is desired, one or more intermediate boundary layers are added over the core by any number of molding operations, including casting, compression molding, and/or injection molding. The cover is then formed over the core and intermediate boundary layers, if present, through casting, compression molding, or injection molding.
In an injection molding process, golf balls are typically created by the injection molding of a fluid stock material around a pre-formed core. In the case of a two-component golf ball, the fluid stock material is the cover material used for the golf ball. The injection molding process is also suitable for golf balls having one or more intermediate layers disposed between the core and the cover. Injection molding devices generally have two separate and mating hemispheric halves that form a cavity in which the golf ball is created. The injection mold also includes a plurality of retractable pins that hold the core in place while the fluid stock (intermediate layer material or cover material) fills the void between the core and the inside walls of the hemispheric mold halves. After the fluid stock of interest has finished entering this void and before the fluid stock has completely hardened, the retractable pins are withdrawn, and the fluid stock material fills the voids created by the retractable pins.
In cast molding, a themoset material is introduced into a mold half and allowed to partially cure before placement of a core therein. The mold half is then mated with an opposing mold half, and the mold is allowed to cure to form the cover.
In compression molding, two blanks are placed on a core and then this structure is placed within a mold. The blanks are then compression molded over the core to form a cover.
All of these traditional molds have a planar parting line that creates difficulties in placing dimples that intersect or lie on the equator of a golf ball.
U.S. Pat. No. 5,147,657, (""657 patent) issued to Giza discloses a mold device having an improved retractable pin mechanism. The mold includes two gates positioned at each pole of the mold cavity. See, e.g., FIG. 2 of ""657 patent. This makes balancing less critical and reduces shifting of the core during molding operations.
As another example, U.S. Pat. No. 5,112,556 (""556 patent), issued to Miller discloses a molding apparatus for the manufacture of golf balls. The ""556 patent discloses a mold that has an alignment means in the form of mating inclined surfaces for precise alignment of the mold halves during operation. In addition, one or more gates are positioned at one or more poles of the mold cavity so that no cold runners or flashings are formed on the golf ball that would require removal.
U.S. Pat. No. 5,122,046 (""046 patent), issued to Lavallee et al. discloses an injection mold device for a two-piece golf ball which, when removed form the mold, does not have any gate vestige and has only a minimal flashline around the ball. The mold of the ""046 patent uses a plurality of tunnel gates on one of the hemispherical surfaces, wherein the tunnel gates are vertically offset from the parting line of the mold. See FIG. 3 of ""046 patent.
U.S. Pat. No. 5,892,567 (""567 patent), issued to Cavallaro et al. discloses a method of making a golf ball having multiple layers. The ""567 patent further discloses an injection molding device for forming golf balls. The injection molding device includes a mold having either edge gates (FIGS. 1 and 2), or sub-gates (FIG. 2(a)). The ""567 patent teaches that edge gates allow the final golf balls to be connected and removed from the mold together.
One non-traditional mold process is disclosed in Solheim, U.S. Pat. No. 4,653,758 for a Golf Ball. As disclosed in Solheim, each of the mold halves have a rim with a wave configuration that has alternating lands and recesses. Each mold half of Solheim has five lands and five recesses that correspond to a pair of blanks that are compression molded to form a cover that has traditional dimples on the equator. The molds of Solheim must be used with the special blanks.
These current golf ball manufacturing processes continue to suffer from a number of disadvantages such as allowing for dimples on the equator, and being limited to traditional dimples for the surface of the golf ball. What is needed is a mold that allows for a surface pattern on the equator, whether traditional dimples or not, and a mold that is applicable to many molding processes.
The present invention is able to provide a novel solution to the problem of a planar parting line on a golf ball by redesigning a mold for forming the golf ball. The present invention accomplishes this solution by having a mold with mold halves that each have non-planar parting lines.
One aspect of the present invention is a mold for a golf ball having a first mold half and a second mold half. The first mold half has a body with an internal cavity and a perimeter having a non-planar surface with alternating extensions and indentations. There are at least ten extensions and at least ten indentations on the perimeter. The second mold half has a body with an internal cavity and a perimeter having a non-planar surface with alternating extensions and indentations. There are at least ten extensions and at least ten indentations on the perimeter of the second mold half. The extensions of the first mold half engage with corresponding indentations of the second mold half, and indentations of the first mold half engage with corresponding extensions of the second mold half.
Another aspect of the present invention is a mold for a golf ball having a first mold half and a second mold half. The first mold half has a body with an internal cavity and a perimeter having a non-planar surface with alternating extensions and indentations. Each of the extensions has a curved apex, and each of the indentations has a curved depression. The second mold half has a body with an internal cavity and a perimeter having a non-planar surface with alternating extensions and indentations. Each of the extensions has a curved apex, and each of the indentations has a curved depression. The extensions of the first mold half engage with corresponding indentations of the second mold half, and indentations of the first mold half engage with corresponding extensions of the second mold half.
Yet another aspect of the present invention is a method for forming a cover on a golf ball precursor product with a non-planar parting line. The method includes placing the golf ball precursor product in a first mold half. The first mold half has a body with an internal cavity and a perimeter having a non-planar surface with alternating extensions and indentations. The method also includes mating the first mold half with a second mold half. The second mold half has a body with an internal cavity and a perimeter having a non-planar surface with alternating extensions and indentations. The extensions of the first mold half engage with corresponding indentations of the second mold half, and indentations of the first mold half engage with corresponding extensions of the second mold half. The method also includes forming a cover on the golf ball precursor product with a non-planar parting line.
The method may also include introducing a castable material in semi-liquid or liquid form into each of the first mold half and the second mold half prior to placing the golf ball precursor product into the first mold half. Forming the cover may include curing the castable material into a cover. Forming the cover may alternatively include injecting an injectable material into a cavity formed by the mating of the first mold half and the second mold half with the golf ball precursor product within the cavity. Further, forming the cover may include compression molding a plurality of blanks about the golf ball precursor product.
It is a primary object of the present invention to provide a mold for a golf ball having a non-planar parting line.
It is an additional object of the present invention to provide a method for forming a golf ball with a non-planar parting line.
Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings.